Infrared imaging is useful for detecting electromagnetic radiation at wavelengths beyond that which is visible to the human eye. Infrared imaging has applications for detecting people and/or machines by their emitted heat which is a form of infrared radiation. Such infrared imaging can be performed at night or when clouds or smoke would otherwise obscure normal vision. Infrared imaging is also important to provide detailed thermal images from space, or from a high altitude using an airplane or an unmanned aerial vehicle (UAV).
Many different types of infrared sensors are known in the art including bolometers and quantum detectors. Quantum detectors such as mercury cadmium telluride (MCT) detectors are highly sensitive but require cooling down to cryogenic temperatures. The cooling of MCT detectors consumes considerable electrical power and typically requires a cryostat. For satellite and UAV applications, the power consumption and weight of cryogenically-cooled quantum detectors can be limiting factors which prevent a scaling of quantum detectors to larger sizes.
Over the past decade, resistive bolometers have made significant inroads in room-temperature infrared imaging. However, in order to achieve a sufficient level of sensitivity, the resistive bolometers need to operate over an entire range of 7-14 μm where the blackbody emission peak lies at room temperature. Additionally, resistive bolometers do not enable sufficient standoff for many remote infrared sensing applications. Resistive bolometer array sizes currently remain below one megapixel which significantly limits resolution and the field of view for these devices.
What is needed is an infrared sensor and infrared sensor array that operates without cryogenic cooling and which provides a sensitivity higher than that of current resistive bolometers and preferably approaching or even exceeding that of conventional quantum detectors.
The present invention addresses this need by providing methods for fabricating thermal microphotonic sensors and sensor arrays which utilize heat provided by incident infrared radiation to change a coupling of light between one or more optical waveguides and optical resonators in the sensors and sensor arrays. Operation of the thermal microphotonic sensors and sensor arrays of the present invention can theoretically be more sensitive than other available types of uncooled detectors including resistive bolometers
These and other advantages of the present invention will become evident to those skilled in the art.